This invention relates generally to an electronic scanner or printer and more particularly to such a scanner or printer that employs a waveguide array.
Currently, document scanners, fax machines, and photocopiers use either reduction optics systems or contact image sensor (CIS) assemblies. Reduction optics systems essentially form an image of the area to be scanned on an image sensor, such as a charge coupled device (CCD), that is much smaller than the scanned line or area. In order to reduce the length of the scan head, mirrors are used to fold the optical path. In CIS assemblies, on the other hand, a long, page wide sensor is either placed in close proximity to the document or object to be scanned, or a relay lens, such as a gradient index (GRIN) lens array, is used to create a 1:1 image of the document on the image sensor.
These systems have important drawbacks. The problems with the reduction optics are their size, the cost of the mirrors and lenses, and the difficulty in aligning multiple mirrors. The problems with CIS systems are the high cost of the sensors, the difficulty in manufacturing butted 600 dpi detector arrays with no dropouts, and the limited depth of field and resolution available with lens arrays.
An alternative method for guiding light from individual pixels of the object to be scanned to respective image sensor pixels is through fiber optics. U.S. Pat. No. 4,760,421 to Margolin and U.S. Pat. No. 5,155,790 to Hwang illustrate several examples of scanners and printers known in the prior art that use fiber optic bundles. Though such devices address the problems associated with reduction optics, they are still difficult to manufacture.
U.S. Pat. No. 4,760,421 to Margolin discloses electronic scanners and printers that employ fiber optic bundles. The bundles are non-coherent in the sense that there is no predetermined relationship between the ends of the fibers in the first face of the bundle and the opposite ends of the fibers in a second face.
Another scanner or printer using a fiber optic bundle is disclosed in U.S. Pat. No. 5,155,790 to Hwang. The Hwang reference teaches a fiber optic bundle comprising ribbons of square fibers where the ribbons are set side by side at one end of the bundle and stacked at the other. Each square fiber of each ribbon comprises multiple rows and columns of (core) fibers each with a cladding to ensure maximal internal reflection of light.
Scanners and printers using fiber optic bundles have not been commercially successful in the marketplace because each fiber is an individual element that must be manipulated. When as many of 5000-10000 of such fibers are used to yield high quality images, the fiber optic bundle becomes quite unwieldy.
Accordingly, a need remains for a scanner or printer that addresses the problems of bulkiness, cost and complexity existent in prior art optical imaging and printing devices.